diff --git a/http-internal.h b/http-internal.h
index 90fd7928..ba6e49ef 100644
--- a/http-internal.h
+++ b/http-internal.h
@@ -71,10 +71,11 @@ struct evhttp_connection {
 	ev_uint64_t max_body_size;
 
 	int flags;
-#define EVHTTP_CON_INCOMING	0x0001	/* only one request on it ever */
-#define EVHTTP_CON_OUTGOING	0x0002  /* multiple requests possible */
-#define EVHTTP_CON_CLOSEDETECT  0x0004  /* detecting if persistent close */
-#define EVHTTP_CON_AUTOFREE 0x0008  /* set when we want to auto free the connection */
+#define EVHTTP_CON_INCOMING	0x0001       /* only one request on it ever */
+#define EVHTTP_CON_OUTGOING	0x0002       /* multiple requests possible */
+#define EVHTTP_CON_CLOSEDETECT	0x0004   /* detecting if persistent close */
+/* set when we want to auto free the connection */
+#define EVHTTP_CON_AUTOFREE	EVHTTP_CON_PUBLIC_FLAGS_END
 
 	struct timeval timeout;		/* timeout for events */
 	int retry_cnt;			/* retry count */
diff --git a/http.c b/http.c
index 909af5e1..fd7ce3cb 100644
--- a/http.c
+++ b/http.c
@@ -2342,13 +2342,14 @@ void evhttp_connection_set_family(struct evhttp_connection *evcon,
 int evhttp_connection_set_flags(struct evhttp_connection *evcon,
 	int flags)
 {
-	if (flags & ~(EVHTTP_CON_REUSE_CONNECTED_ADDR)) {
+	int avail_flags = 0;
+	avail_flags |= EVHTTP_CON_REUSE_CONNECTED_ADDR;
+
+	if (flags & ~avail_flags || flags > EVHTTP_CON_PUBLIC_FLAGS_END)
 		return 1;
-	}
+	evcon->flags &= ~avail_flags;
 
-	evcon->flags &= ~(EVHTTP_CON_REUSE_CONNECTED_ADDR);
-
-	evcon->flags |= EVHTTP_CON_REUSE_CONNECTED_ADDR;
+	evcon->flags |= flags;
 
 	return 0;
 }
diff --git a/include/event2/http.h b/include/event2/http.h
index 09fd8e1c..e9978207 100644
--- a/include/event2/http.h
+++ b/include/event2/http.h
@@ -637,7 +637,10 @@ EVENT2_EXPORT_SYMBOL
 void evhttp_connection_set_family(struct evhttp_connection *evcon,
 	int family);
 
-#define EVHTTP_CON_REUSE_CONNECTED_ADDR  0x0008  /* reuse connection address on retry */
+/* reuse connection address on retry */
+#define EVHTTP_CON_REUSE_CONNECTED_ADDR	0x0008
+/* Padding for public flags, @see EVHTTP_CON_* in http-internal.h */
+#define EVHTTP_CON_PUBLIC_FLAGS_END	0x100000
 /**
  * Set connection flags.
  *